In recent years, with rapid development in mobile electronics such as notebook computers or mobile phones including display panels such as liquid crystal display panels, there is an increasing demand for reducing the thicknesses and the sizes of the display panels.
In general, each liquid crystal display panel includes a pair of facing substrates (i.e., a thin film transistor (TFT) substrate and a color filter (CF) substrate), a liquid crystal layer between the pair of substrates, and a sealing material provided in a frame shape to allow the pair of substrates to adhere to each other, and to encapsulate liquid crystal between the substrate.
Such liquid crystal display panels are utilized for mobile devices such as mobile phones, mobile information terminal equipment, and portable game players. In such a mobile device, there is a very strong need for expanding a pixel region in a liquid crystal display panel in view of improving the portability and reducing the size and the thickness of the display panel. It is thus necessary to reduce the external portion (i.e., the frame region) of a display region in the liquid crystal display panel as much as possible to expand the pixel region in the liquid crystal display panel. In other word, the liquid crystal display panel needs to have a narrower frame. It is however, necessary to reduce the width of the sealing material located in the frame region to obtain the narrower frame. With a decrease in the width of the sealing material, the bonding area of the sealing material decreases, thereby reducing the adhesive strength and the bulk strength of the sealing material.
It is generally most efficient to form a sealing material with a constant width to surround a display region. Thus, the sealing material in a wide frame region adjacent to a terminal region is formed to have a same width as the sealing material in a narrow frame region.
For example, a liquid crystal display panel has been suggested (see, e.g., PATENT DOCUMENT 1), which includes a terminal region, a display region, and a frame region. The terminal region includes a plurality of terminals receiving signals from the outside. The display region displays images. The frame region is provided around the display region. The sealing material is formed in a frame shape to surround the display region. The sealing material has a constant height in a wide frame region adjacent to a terminal region and in a narrow frame region.
Another liquid crystal display panel has been suggested (see, e.g., PATENT DOCUMENT 2), which is formed by linearly applying a sealing material with a constant width onto the surface of one of a TFT substrate or a CF substrate to surround a display region.